Aphids are small yellowish to greenish insects often found on the underside of leaves and on new growth. Aphids on birch typically feed on the leaf veins and produce large amounts of honeydew, a sticky material which may attract ants or become covered with a black growth of sooty mold. Developing leaves which have been injured by aphid feeding may show a typical “corrugated” or wrinkled growth pattern, with the insects often found on the underside in the distortions. Some yellowing of the leaves may be observed with heavy aphid infestations.
Use Integrated Pest Management (IPM) for successful plant problem management.
Select non-chemical management options as your first choice!
- Hand-wipe or prune to control small, isolated infestations when practical.
- Wash aphids from foliage with a strong stream of water.
- Encourage natural enemies, including ladybird beetles, lacewings, and parasitic wasps.
- Control honeydew-feeding ants, which may protect aphid colonies.
- Provide proper nutrition. High levels of nitrogen in the foliage encourages aphid reproduction. Switch to a slow-release or low-nitrogen fertilizer.
IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.
- Thorough coverage of foliage is important, including lower leaf surfaces.
- Apply when aphids are first noticed.
- Homeowners should not make foliar applications to trees over 10 ft tall.
- Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.
Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.